1. Field of the Invention
This invention relates to an endoscope apparatus having a tip cover detachably mounted on a tip portion of an insertion portion thereof to be inserted into a body cavity (including a corporeal tube).
2. Description of the Related Art
In general, a side-view endoscope of a tip-cover detachable type is known, for example, from Jpn. Pat. Appln. KOKAI Publication No. 4-314439, in which a tip cover is detachably mounted on a tip portion of an insertion portion to be inserted into a body cavity. The tip cover of an endoscope of this type is made of a relatively hard material.
Further, Jpn. UM Appln. KOKAI Publication No. 51-103891 discloses an elastic cover which covers the entire insertion portion of an endoscope. Moreover, Jpn. Pat. Appln. KOKOKU Publication No. 2-54734 discloses a cover which covers the insertion portion of an endoscope and has a channel formed therein for inserting therethrough a medical treatment tool.
Deformable relatively-soft components, such as a coating member for a bendable portion and a flexible tube, etc., are generally provided rearward of a tip structure constituting a tip portion of the insertion portion of an endoscope. In the conventional endoscope of the tip-cover detachable type, such soft components are liable to be cut or have holes pierced at the time of the tip cover being attached to or detached from the tip structure.
In the cases of Jpn. UM Appln. KOKAI Publication No. 51-103891 and Jpn. Pat. Appln. KOKOKU Publication No. 2-54734, where substantially the entire insertion portion of the endoscope is covered with a long cover, it is necessary to detach and clean the cover after the endoscope is used, but it is not necessary to clean the insertion portion itself since the insertion portion is not contaminated by virtue of the cover. However, attachment or detachment of the long cover to or from the insertion portion is not easy. Cleaning of the long cover is also not easy.
In a case where a disposable long cover is used, a person (patient) to be examined must bear its relatively high expense. In other words, the treatment bill is inevitably increased.
Furthermore, in the case of Jpn. Pat. Appln. KOKAI Publication No. 4-314439 where a hard tip cover is mounted on a hard tip structure, looseness may occur between the tip cover and the tip structure because it is difficult to sufficiently fit hard components to each other. If the looseness therebetween causes misalignment therebetween during a medical treatment using the endoscope, the field of view of the endoscope may be narrowed by the tip cover.
If the tip cover is firmly fixed to the tip structure and there is no play therebetween, detachment of the former from the latter is extremely difficult. Therefore, an excessive force must be applied to the tip cover to attach the tip cover to the tip structure or detach the same therefrom. As a result, it is highly possible that the tip cover mat be damaged or deformed.